高压直流输电系统换流变分接开关专用保护方案OA

Converter transformers(abbreviated as converters)are the core equipments in high voltage direct current(HVDC)transmission systems,which determine the security and stability of the power system.In recent years,there have been multiple incidents of converter damage and DC shutdown caused by the failures of tap changer for converter.From the perspective of relay protection,traditional converter transformer protection-schemes have poor maneuverability and weak sensitivity to the failures of tap changer.Based on the study of the fault mechanism of tap changer,a dedicated protection scheme for tap changer of converter is proposed.This scheme collects and utilizes both the electrical and non-electrical information of the converter,introduces a sine signal half cycle absolute value integration algorithm,and consists of a fast differential protection criterion that takes into account the tap information and a non-electrical quantity detection criterion.Theoretical analysis and simulation experiments show that,without reducing the reliability,this scheme has a faster action speed of 15 ms compared to traditional protection of converter,and can solve the problem of converter damage caused by the faults of tap changer due to long cutting time.